Minimally invasive interventions are acquiring an increasing significance in the field of clinical surgery. Although, only a few years ago, relatively large areas of the operating site were opened up for small surgical interventions in order to allow the surgeon to navigate using natural landmarks, it can be observed that nowadays a large number of these interventions are carried out using laparoscopy and optical assistance in the form of endoscopy. Robot-assisted surgery is a further development of traditional laparoscopy that has made inroads meanwhile in a number of areas of medicine, for example, in urology, gynecology or cardiology. It is in the process of becoming part of the everyday medical scene.
A laparoscopy robot is known, for example, in the form of the “da Vinci” model from the company Intuitive Surgical. This robot comprises a first instrument arm that has an endoscope at its front extremity. Up to three further instrument arms hold laparoscopic instruments.
Both for the endoscope and for each of the instruments, a trocar is placed in the patient in each case. The trocar is used to introduce the respective tool into the patient in order to then carry out a robot-assisted, minimally invasive intervention on the patient.
It may be observed in the clinical workflow of such an intervention that a considerable proportion of the surgical preparation time consists in inserting the tools controlled by the robot on the instrument arms into the trocars that have already been set up in the run-up to the surgery or in preparing for the insertion of these tools. For this purpose, the individual articulations, linear actuators and so forth on the respective robotic arm are connected without power and the instrument arm is adjusted by hand in such a way that, through the corresponding adjustments of the articulations or of the underlying kinematics for the robot, the instrument (which is still outside the patient), comes to rest in a predetermined relative position, which may also be understood as a target position, with respect to the trocar. Here the trocar is already placed in an individual spatial location in the patient (which location is more or less spatially fixed) with a trocar providing a trocar axis, generally the central longitudinal axis, as the direction in which the longitudinal tools are introduced axially into the patient via the trocar.
In the da Vinci System, the instrument arm can be oriented together with the instrument (usually in three dimensions) such that the longitudinal axis of the instrument that is being held runs coaxially to the trocar axis, but the instrument remains, however, at a distance from the trocar and is located outside the patient. In other words, the predetermined relative position is such that the instrument on the instrument arm can impact on or penetrate the trocar with a movement in a straight line. The instrument can then still be moved unidimensionally in this axial direction towards the trocar until it touches it. The instrument arm is then again mechanically coupled; the instruments are then introduced robotically into the respective trocar with a movement in a straight line. In other words, there is therefore a predeterminable relative position for the instrument arm that can be targeted, which position is predeterminable with respect to a trocar placed in a patient.
This procedure of manual adjustment assumes that the staff carrying out the reparation has some experience and it is very time-consuming. Even in mechanically complex systems, the manual adjustment is very elaborate since, for safety reasons, a very high friction level has to be selected in the articulations even when in power-free operation. In the case of the aforementioned da Vinci System, this procedure has to be repeated four times when all the robot arms are used.